IES TM-28-20

This document provides guidance and recommended procedures for sampling, test intervals and duration, and a method for long-term luminous flux maintenance projection for LED lamps and luminaires. The intent is to help product manufacturers and users, standards developing bodies, and other organizations to avoid any unnecessary burdens related to excessive product testing. A balance was sought between testing time and effort on one side, and sufficient statistical rigor on the other. A direct and a combined method for luminous flux maintenance projection are proposed; the latter allows the use of luminous flux maintenance data obtained for both the lamp or luminaire being tested as well as the LED sources used in it.